898-899 / 1195
4
Methylumbelliferyl phosphate) is cycled in and out of the SPR®. The conjugate enzyme catalyzes the hydrolysis of this substrate into
1
a fluorescent product (4-Methylumbelliferone), the fluorescence of which is measured at 450 nm.
2
3
At the end of the assay, the results are analyzed automatically by the instrument, which generates a test value for each sample. This
4
value is compared to a set of stored standards (thresholds) and each result is interpreted (positive or negative).
5
6
General Information
7
The current classification of the genus
Listeria
includes six species that are non-spore-forming, short, motile, Gram positive rods.
8
These organisms are catalase positive, oxidase negative, hydrolyze esculin and ferment glucose without gas production.
Listeria
can
9
grow at wide temperature and pH ranges and can tolerate high concentrations of sodium chloride (1,2).
10
11
Members of the genus
Listeria
are ubiquitous and certain species are pathogenic.
Listeria
have been isolated from various food
12
products including dairy products, meats, vegetables and seafood, as well as from environmental samples taken, in particular, from
13
food processing plants.
14
15
In humans, listeriosis is usually associated with the species
L. monocytogenes
and may cause meningitis, septicemia, encephalitis, and
16
abortions. Groups at greatest risk include pregnant women, neonates, immunocompromised patients and the elderly (3). Traditional
17
methods for the detection of
Listeria monocytogenes
involve enrichment that includes several tedious and labor-intensive steps. In
18
addition, current culture methods require lengthy incubation periods to achieve final results (4,5).
19
20
Scope of method
21
The VIDAS®
L. monocytogenes
Xpress (LMX) test was evaluated in the
Performance Tested Methods
program for the detection of
22
Listeria monocytogenes
in smoked white fish, cooked shrimp, peanut butter, frozen spinach, deli ham, vanilla ice cream and processed
23
cheese. The method was compared to the US Food and Drug Administration
Bacteriological Analytical Manual
(FDA BAM) and the
24
US Department of Agriculture Food Safety and Inspection Service
Microbiology Laboratory Guidebook
(USDA-FSIS MLG), and the
25
AOAC INTERNATIONAL
Official Method
993.12 reference culture procedures (4, 5, 6). The VIDAS LMX was also evaluated in
26
the GovVal program for the detection of
Listeria monocytogenes
in ready to eat meats (liver paté, hot dogs, raw fermented sausage,
27
sliced deli turkey and sliced deli ham) in comparison to the Health Canada, Health Products and Food Branch
Compendium of
28
Analytical Methods
reference method (7).
29
30
Methods and Materials
31
32
Test Kit Information
33
34
a)
Kit Name -
VIDAS®
L. monocytogenes
Xpress (LMX)
35
b)
Catalog Number – Reference 30123
36
PTM Certification Report